package 面试;


import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.ReentrantReadWriteLock;

class MyCache{
    private volatile Map<String, Object> map = new HashMap<>();
    private ReentrantReadWriteLock rwLock = new ReentrantReadWriteLock();

    public void put(String key, Object value){

        rwLock.writeLock().lock();
        try{
            System.out.println(Thread.currentThread().getName() + "\t正在写入：" + key);
            try { TimeUnit.MILLISECONDS.sleep(300);} catch (InterruptedException e) {e.printStackTrace(); }
            map.put(key, value);
            System.out.println(Thread.currentThread().getName() + "\t写入完成：" + value);
        }catch (Exception e){
            e.printStackTrace();
        }finally {
            rwLock.writeLock().unlock();
        }
    }

    public void get(String key){

        rwLock.readLock().lock();
                try{
                    System.out.println(Thread.currentThread().getName() + "\t正在读取：" + key);
                    try { TimeUnit.MILLISECONDS.sleep(300);} catch (InterruptedException e) {e.printStackTrace(); }
                    Object result = map.get(key);
                    System.out.println(Thread.currentThread().getName() + "\t读取完成：" + result);
                }catch (Exception e){
                    e.printStackTrace();
                }finally {
                    rwLock.readLock().unlock();
                }
    }
}


public class ReadWriteLockDemo {
    public static void main(String[] args) {

        MyCache myCache = new MyCache();

        for (int i = 0; i < 5; i++) {
            final int temp = i;
            new Thread(() -> {
                myCache.put(temp+"",temp+"");
            }, String.valueOf(i)).start();
        }

        for (int i = 0; i < 5; i++) {
            final int temp = i;
            new Thread(() -> {
                myCache.get(temp+"");
            }, String.valueOf(i)).start();
        }
    }

}
